Simultaneous and continuous biosorption of Cr and Cu (II) ions from industrial tannery effluent using almond shell in a fixed bed column

The study on performance of almond shell in the simultaneous removal of Cr ions and Cu (II) from tannery effluent was investigated in a laboratory scaled fixed bed column. The characterization of the almond shell was examined using SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy). FTIR analysis of almond shell revealed the existence of hydroxyl, carbonyl and aliphatic functional groups responsible for the adsorption of the metal ions. The breakthrough curve basically was used to study the efficiency of the packed bed adsorption system with the almond shell. It was observed that the breakthrough is a function of flow rate, initial metal concentrations and the packed bed height. The column adsorption effectiveness increases with the rise in the influent concentration, bed depth and reduces with the rise in the flow rate. The column parameters analysed indicated the efficiency of the column at flow rate of 3.0 ​ml/min, bed height of 7.0 ​cm and concentrations of 67.5 ​mg/L and 7.0 ​mg/L for Cr ions and Cu (II) ions respectively. The proportional removal of Cu (II) and Cr ions at optimal values were 70.0 and 65.9% with adsorption capacities of 2.39 and 21.92 ​mg/g respectively. Column adsorption kinetics was sufficiently defined with Thomas and Yoon and Nelson models. The model parameters, such as mass transfer coefficient and kinetic parameters were determined. Comparison between experimental breakthrough curves to the breakthrough profiles determined using Thomas and Yoon-Nelson models gives prominent correlation coefficients (R²) indicating satisfactory fit for both metals.